How ASDIC and Type 271 divided the submarine search

The wheelhouse layout reflects years of Royal Navy ASDIC experience: operators needed a quiet space in which to listen and maintain a track. The service had used ASDIC since the 1920s and developed variants for different escorts and weapons. ASDIC tracked submerged targets, while centimetric Type 271 radar could reveal surfaced U-boats and periscopes. Sackville's lantern-like radar housing protected delicate equipment from North Atlantic waves and spray while allowing the set to operate. Radar detection of a surfaced submarine could lead to illumination and four-inch gunfire, closing an escape route from acoustic detection. The sensors supported different phases of an attack, although their usefulness still depended on operators and the target's circumstances.